Thieves pinch two computers a month from Parliament, it has been revealed.

A total of 25 computers were reported stolen over the past year, with crooks also stealing six mobile phones from one of the most heavily-guarded buildings in the country. Ten computers vanished in May alone.

Lib Dem MP John Thurso, who represents the House of Commons Commission, told MPs: "The House authorities and the Metropolitan Police have jointly implemented a crime prevention plan, including strong advice to lock up valuable items and to lock office doors at the end of the working day.

"Nightly security patrols in both Houses report exceptions, which are followed up by the Serjeant at Arms. During these patrols, any offices found insecure are now locked."

Six months ago Home Affairs Select Committee chairman Keith Vaz fell victim to thieves when a laptop and iPad were stolen from his Westminster office.

He said then: "A great deal of effort is taken to protect the outside of the building, but we need a more robust approach to security inside the building.

"We need to ensure the security of the building is not compromised."

Mr Thurso was answering a written Parliamentary question from Labour MP Tom Watson (West Bromwich East) on the day the head of Commons security, Serjeant at Arms Jill Pay, announced that she would retire in January.